There were cheers in the public gallery as the sentence was handed down by Mr Justice Royce, and Watkins was seen visibly shaking as he left the dock.

Prosecutor Chris Clee QC described him as a "determined and committed paedophile", while Mr Justice Royce said what he and his co-defendants did "plumbs new depths of depravity", and he had shown "evident delight" in abusing children.

The judge said the singer had displayed "an almost complete lack of remorse" for his behaviour, and posed a "significant risk" to young women and children.

And on hearing Watkins had told a probation officer he did not know what lengths he would have gone to with children had he not been arrested, Mr Justice Royce added: "It's difficult to imagine anything much worse."

"I am satisfied that you are a deeply corrupting influence. You are highly manipulative.

"You are a sexual predator. You are dangerous. The public, and in particular young females and children, need protection from you."

Ringing a friend from prison the day after entering his guilty pleas, Watkins said: "It was like either me go up there and say 'Come on, it wasn't that bad, nobody got hurt'.

"I do my charm or do I end up making things worse for myself or do I just say I was off my head and can't remember?"

Discussing his possible sentence, he added: "I'm going to put out a statement on the 18th now (the day of his sentencing) just to say it was mega lolz, I don't know what everyone is getting so freaked out about."

Sentenced alongside Watkins were two women, who had admitted a string of sex abuse charges against their own children.

One was a 21-year-old, who cannot be named, who admitted aiding and abetting an attempted rape, two counts of sexually assaulting a child aged under 13 years, taking indecent photographs of children and distributing indecent photographs of children.

She was sentenced to 14 years in jail.

The other was a 24-year-old woman, who pleaded guilty to sexually assaulting a child aged under 13, and also admitted charges of sexually assaulting a child under 13 by touching, conspiracy to rape a child under 13, conspiracy to sexually assault a girl under 13, two counts of indecent photographs of a child and distributing indecent photographs of children.

She was sentenced to 17 years in jail.

Speaking after the sentence, Detective Chief Inspector Peter Doyle - South Wales Police's senior investigating officer - said: "Today’s sentence reflects the gravity of the crimes that have been committed. The three paedophiles responsible for the terrible abuse of two babies have now been brought to justice.

"The investigation uncovered the most disturbing child abuse evidence I have seen in my 28 years as a police officer.

"The guilty pleas have ensured that the jury were spared from viewing evidence that would have been extremely traumatic.

"The safeguarding of children has been an absolute priority for the investigation team. Today’s sentence does not mark the end of our investigations and we will work tirelessly to identify any other victims or witnesses and seek the justice they deserve. In the last few weeks we have received further information that will now be looked at by the investigation team.

"There are also investigations being conducted by other police forces around the world including Germany and the United States.

"Above all this investigation has been focused on the protection of children and my thoughts today remain with those victims.

"We would encourage anyone who has been affected by this case or other cases of child abuse to contact South Wales Police on 029 20634184 or the NSPCC on 0808 800 5000."